## REGEX

 . \$string1 = "Hello World\n"; if (\$string1 =~ m/…../) { print "\$string1 has length >= 5\n"; } ( ) \$string1 = "Hello World\n"; if (\$string1 =~ m/(H..).(o..)/) { print "We matched ‘\$1’ and ‘\$2’\n"; } Output: We matched ‘Hel’ and ‘o W’; + \$string1 = "Hello World\n"; if (\$string1 =~ m/l+/) { print "There are one or more consecutive letter \"l\"’s in \$string1\n"; } Output: There are one or more consecutive letter "l"’s in Hello World ? \$string1 = "Hello World\n"; if (\$string1 =~ m/H.?e/) { print "There is an ‘H’ and a ‘e’ separated by "; print "0-1 characters (Ex: He Hoe)\n"; } ? \$string1 = "Hello World\n"; if (\$string1 =~ m/(l.+?o)/) { print "The non-greedy match with ‘l’ followed by one or "; print "more characters is ‘llo’ rather than ‘llo wo’.\n"; } * \$string1 = "Hello World\n"; if (\$string1 =~ m/el*o/) { print "There is an ‘e’ followed by zero to many "; print "’l’ followed by ‘o’ (eo, elo, ello, elllo)\n"; } {M,N} \$string1 = "Hello World\n"; if (\$string1 =~ m/l{1,2}/) { print "There exists a substring with at least 1 "; print "and at most 2 l’s in \$string1\n"; } […] \$string1 = "Hello World\n"; if (\$string1 =~ m/[aeiou]+/) { print "\$string1 contains one or more vowels.\n"; } | \$string1 = "Hello World\n"; if (\$string1 =~ m/(Hello|Hi|Pogo)/) { print "At least one of Hello, Hi, or Pogo is "; print "contained in \$string1.\n"; } \b \$string1 = "Hello World\n"; if (\$string1 =~ m/llo\b/) { print "There is a word that ends with ‘llo’\n"; } \w \$string1 = "Hello World\n"; if (\$string1 =~ m/\w/) { print "There is at least one alphanumeric "; print "character in \$string1 (A-Z, a-z, 0-9, _)\n"; } \W \$string1 = "Hello World\n"; if (\$string1 =~ m/\W/) { print "The space between Hello and "; print "World is not alphanumeric\n"; } \s \$string1 = "Hello World\n"; if (\$string1 =~ m/\s.*\s/) { print "There are TWO whitespace characters, which may"; print " be separated by other characters, in \$string1"; } \S \$string1 = "Hello World\n"; if (\$string1 =~ m/\S.*\S/) { print "There are TWO non-whitespace characters, which"; print " may be separated by other characters, in \$string1"; } \d \$string1 = "99 bottles of beer on the wall."; if (\$string1 =~ m/(\d+)/) { print "\$1 is the first number in ‘\$string1’\n"; } Output: 99 is the first number in ’99 bottles of beer on the wall.’ \D \$string1 = "Hello World\n"; if (\$string1 =~ m/\D/) { print "There is at least one character in \$string1"; print " that is not a digit.\n"; } ^ \$string1 = "Hello World\n"; if (\$string1 =~ m/^He/) { print "\$string1 starts with the characters ‘He’\n"; } \$ \$string1 = "Hello World\n"; if (\$string1 =~ m/rld\$/) { print "\$string1 is a line or string "; print "that ends with ‘rld’\n"; } \A \$string1 = "Hello\nWorld\n"; if (\$string1 =~ m/\AH/) { print "\$string1 is a string "; print "that starts with ‘H’\n"; } \z \$string1 = "Hello\nWorld\n"; if (\$string1 =~ m/d\n\z/) { print "\$string1 is a string "; print "that ends with ‘d\\n’\n"; } [^…] \$string1 = "Hello World\n"; if (\$string1 =~ m/[^abc]/) { print "\$string1 contains a character other than "; print "a, b, and c\n"; }

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